Vehicle powertrain with dual-independent transmissions

ABSTRACT

A dual-independent powertrain for a vehicle includes a transmission enclosure that houses a first transmission and a second transmission that are mechanically decoupled from each other. The enclosure includes a central frame, a first enclosure cover that interfaces with the central frame to collectively define a first transmission region on a first side of the central frame, and a second enclosure cover that interfaces with the central frame to collectively define a second transmission region on a second side of the central frame. The first transmission is housed within the first transmission region, and the second transmission is house within the second transmission region. Each transmission includes a motor-interfacing shaft that interfaces with a respective electric motor, a drive-interfacing shaft that interfaces with a respective drive wheel of a vehicle, and a multi-stage gear train mechanically coupling the motor-interfacing shaft and the drive-interfacing shaft.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional of and claims priority to U.S.provisional patent application Ser. No. 62/052,664, filed Sep. 19, 2014,and titled “Single Ratio Parallel Electric Vehicle Powertrain Device”,the entire contents of which is herein incorporated by reference for allpurposes.

BACKGROUND

Vehicles include a powertrain to mechanically couple one or more drivewheels with a drive source, such as an electric motor or a combustionengine. A powertrain typically includes a transmission, and mayadditionally include the drive source, the drive wheels, and otherintervening components.

SUMMARY

In one aspect of the disclosed subject matter, a dual-independentpowertrain for a vehicle includes a transmission enclosure that houses afirst transmission and a second transmission that are mechanicallydecoupled from each other. The enclosure includes a central frame, afirst enclosure cover that interfaces with the central frame tocollectively define a first transmission region on a first side of thecentral frame, and a second enclosure cover that interfaces with thecentral frame to collectively define a second transmission region on asecond side of the central frame. The first transmission is housedwithin the first transmission region, and the second transmission ishouse within the second transmission region. Each transmission includesa motor-interfacing shaft that interfaces with a respective electricmotor, a drive-interfacing shaft that interfaces with a respective drivewheel of a vehicle, and a multi-stage gear train mechanically couplingthe motor-interfacing shaft and the drive-interfacing shaft. Arespective electric motor interfaces with each motor-interfacing shaftand a respective drive wheel interfaces with each drive-interfacingshaft to provide a dual-independent powertrain in which each motor islocated on the same side of the central frame from the drive wheel withwhich that motor is mechanically coupled.

In another aspect of the disclosed subject matter, a dual-independentpowertrain for a vehicle includes a transmission enclosure that houses afirst transmission and a second transmission that are mechanicallydecoupled from each other. Each transmission includes amotor-interfacing shaft that interfaces with a respective electricmotor, a drive-interfacing shaft that interfaces with a respective drivewheel of a vehicle, and a multi-stage gear train mechanically couplingthe motor-interfacing shaft and the drive-interfacing shaft. Themotor-interfacing shaft and the drive-interfacing shaft of eachtransmission are located on an opposite side of the central frame fromeach other. A respective electric motor interfaces with eachmotor-interfacing shaft and a respective drive wheel interfaces witheach drive-interfacing shaft to provide a dual-independent powertrain inwhich each motor is located on an opposite side of the central framefrom the drive wheel with which that motor is mechanically coupled.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view an example dual-independent powertrain.

FIG. 2 is a side view of the powertrain of FIG. 1.

FIG. 3 is a top view of the powertrain of FIG. 1.

FIG. 4 is a perspective view of the powertrain of FIG. 1 with anenclosure cover removed.

FIG. 5 is a top view of the powertrain of FIG. 1 with hidden featuresshown as dashed lines.

FIG. 6 is a top view of an example vehicle that includes the powertrainof FIG. 1.

FIG. 7 is a perspective view of the vehicle of FIG. 6 that includes thepowertrain of FIG. 1.

FIG. 8 depicts an internal view of another example dual-independentpowertrain.

FIG. 9 depicts a side view of an example dual-independent powertrainwith an enclosure cover removed.

FIG. 10 depicts a side view of the powertrain of FIG. 9 with theenclosure cover installed.

DETAILED DESCRIPTION

The dual-independent powertrains disclosed herein enable two drivesources (e.g., two electric motors) to each provide parallel andindependent drive capability to different wheels of a vehicle viarespective transmissions. The dual-independent powertrains may includeoperationally symmetric transmissions that utilize many of the samecomponents to provide a cost effective vehicle-based solution thatsupports features such as traction control, anti-lock braking, andregenerative braking by way of independent control of the drive sources,transmissions, and drive wheels. The dual-independent powertrains may beconfigured to provide a compact design that utilizes the same or similarparts in each transmission component to reduce the overall cost andcomplexity of the powertrain.

In one aspect of the disclosed subject matter, a dual-independentpowertrain for a vehicle includes a transmission enclosure that houses afirst transmission and a second transmission that are mechanicallydecoupled from each other. The enclosure includes a central frame, afirst enclosure cover that interfaces with the central frame tocollectively define a first transmission region on a first side of thecentral frame, and a second enclosure cover that interfaces with thecentral frame to collectively define a second transmission region on asecond side of the central frame. The first transmission is housedwithin the first transmission region, and the second transmission ishouse within the second transmission region. Each transmission includesa motor-interfacing shaft (also referred to as an axle) that interfaceswith a respective electric motor, a drive-interfacing shaft thatinterfaces with a respective drive wheel of a vehicle, and a multi-stagegear train mechanically coupling the motor-interfacing shaft and thedrive-interfacing shaft. A respective electric motor interfaces witheach motor-interfacing shaft and a respective drive wheel interfaceswith each drive-interfacing shaft to provide a dual-independentpowertrain in which each motor is located on the same side of thecentral frame from the drive wheel with which that motor is mechanicallycoupled.

In another aspect of the disclosed subject matter, a dual-independentpowertrain for a vehicle includes a transmission enclosure that houses afirst transmission and a second transmission that are mechanicallydecoupled from each other. Each transmission includes amotor-interfacing shaft that interfaces with a respective electricmotor, a drive-interfacing shaft that interfaces with a respective drivewheel of a vehicle, and a multi-stage gear train mechanically couplingthe motor-interfacing shaft and the drive-interfacing shaft. Themotor-interfacing shaft and the drive-interfacing shaft of eachtransmission are located on an opposite side of the central frame fromeach other. A respective electric motor interfaces with eachmotor-interfacing shaft and a respective drive wheel interfaces witheach drive-interfacing shaft to provide a dual-independent powertrain inwhich each motor is located on an opposite side of the central framefrom the drive wheel with which that motor is mechanically coupled.

FIG. 1 depicts an example dual-independent powertrain 10. In at leastsome implementations, the powertrain 10 includes two substantiallyidentical and/or symmetric enclosure covers 12, a first electric motor16 a, a second electric motor 16 b, a central housing 14 (also referredto herein as a central frame), a first output shaft 18 a and a secondoutput shaft 18 b (also referred to herein as drive-interfacing shaftsor drive shafts). The covers 12 are depicted in FIG. 1 as separatecomponents from the central housing 14. This configuration may bedesirable in order to provide access to the central housing 14. However,in alternative configurations, the covers 12 and central housing 14 maybe a single component.

Referring to the central housing 14 in further detail, the centralhousing 14 is sufficiently wide and long to house a first gear train 20a and a second gear train 20 b. The particular ratio of the gear train20 may vary and can be selected for the particular application for whichpowertrain 10 is used. The covers 12 are dimensioned to fit against thecentral housing 14 and are fastened to the central housing 14 to providea fluid tight enclosure for the first and second gear train 20 a, 20 bthat is suitable for holding a transmission oil or fluid. The centralhousing 14 has a central plane 15 that extends through it.

Referring to the covers 12 in more detail, the covers 12 may be designedto rigidly fix or otherwise secure the first and second motors 16 a, 16b relative to the central housing 14. Additionally, the covers 12 alsoprovide for efficient function of the first and second motors 16 a, 16 bby increasing the stiffness of the powertrain 10. In alternativeconfigurations, the first and second motors 16 a, 16 b may directlymount to the central housing 14.

Referring to the covers 12 and central housing 14 in more detail, theseelements may be made of any sufficiently rigid and strong material suchas aluminum, steel, high-strength alloys, or composites. The first andsecond gear train 20 a, 20 b, may be made of any materials that aresuitable for use according to the power demands on the powertrain 10.Non-limiting examples of materials include, plastics including nylon,steel, cast iron, or other materials commonly used in powertrainconstruction.

Additional maintenance features of the powertrain 10 may be incorporatedinto the central housing 14 and/or covers 12 to facilitate the fillingand removal of transmission oil or fluid (e.g., gear oil), monitor theamount of oil or fluid, and provide cooling fins or heat sinks to reducethe operating temperature of the oil or fluid. Oil or fluid may be heldwithin the region or region(s) enclosed by the covers 12 and centralhousing 14 via a tight seal created between the covers 12 and thecentral housing 14, which may include one or more perimeter sealinggaskets.

Operationally, the powertrain is symmetrical in function about centralplane 15 shown in FIG. 3. Plane 15 may refer to a plane parallel to thesides of the central housing 14 and equidistant from the cover 12mounting face on either side of the central housing 14. Thus, plane 15is a central plane for the central housing 14 and/or the overallpowertrain.

Referring to the first powertrain 20 a in more detail, FIG. 4 disclosesthe parallel electric powertrain 10 of FIG. 1 with the cover 12 nearestto the first gear train 20 a removed. Shown within the central housing14, is the first gear train 20 a. Notably, the particular number andarrangement of gears shown in FIG. 4 is simply an exemplary arrangement.The configuration of gears will vary depending upon the desired ratioand the particular end use of the parallel electric powertrain 10. Thereare many variations of gear trains that are suitable for use with theinvention, and a person skilled in the art would understand themodification of the gear train for a particular use. Additionally,although gears are shown in the embodiment depicted in FIG. 4, a beltwith pulleys would also be suitable and is considered within the scopeof this disclosure.

The first gear train 20 a mechanically couples and transmits powerbetween the first electric motor 16 a and the first output shaft 18 a(referred to as a drive-interfacing shaft or a drive shaft integratedwith a drive-interfacing shaft of the transmission or gear train). Inthe view shown in FIG. 4, the first electric motor output shaft 21 a(referred to as a motor shaft or a motor shaft integrated with amotor-interfacing shaft of the transmission or gear train) extends fromthe first electric motor 20 a through plane 15 of the central housing14. The first electric motor output shaft 21 a is operable for drivingthe first gear train 20 a and thereby operating the first output shaft18 a. The same configuration may be used for the second electric motor16 b, which is mechanically coupled with and drives a second outputshaft 18 b via a second gear train 20 b and motor output shaft 21 b.Thus, in the configuration of powertrain 10, a first electric motor 16 alocated on a first side of the central plane drives a non-collinearlylocated first output shaft 18 a located on an opposite second side ofthe central plane, and a second electric motor 16 b located on thesecond side of the central plane opposite the first electric motor 16 adrives a non-collinearly located second output shaft 18 b on the firstside of the central plane opposite the second electric motor 16 b. Alsoin this configuration, motor output shafts 21 a, b are not collinearwith each other, whereas output shafts 18 a, 18 b are collinear witheach other.

Referring to the first gear train 20 a and second gear train 20 b inmore detail, the first gear train 20 a and second gear train 20 b eachdefine a direction between the respective electric motor output shaftand output shaft which is coupled by the respective gear train. Thesedirections, define a first direction associated with the first geartrain 20 a and a second direction associated with the second gear train20 b. When transposed on to plane 15, the first direction and seconddirection define an interior angle. The angle may range between justgreater than 0 degrees and 180 degrees. The dual-independent powertrainsdisclosed herein encompass configurations in which the angle is 180degrees which places the first electric motor 16 a and second electricmotor 16 b at a maximum distance for a given gear train lengths andprovides a flat profile for the parallel electric powertrain 10. In anexample configuration, the gear train angle is less than 90 degrees(referred to as a folded configuration). A gear train angle less than 90degrees provides a parallel electric powertrain 10 with a smallervolume, which is desirable in certain applications.

In FIGS. 4 and 5, hidden features are depicted with dashed lines. FIG. 5depicts a top view of powertrain 10 with dashed lines showing hiddenfeatures of first gear train 20 a and second gear train 20 b. Depictedwith dashed lines is the first gear train 20 a which rotationallycouples the first electric motor 16 a to the first output shaft 18 a,and the second gear train 20 b which rotationally couples the secondelectric motor 16 b to the second output shaft 18 b.

FIGS. 6 and 7 depict an example vehicle 30 that includes powertrain 10.Vehicle 30 is a non-limiting example of a vehicle that is suitable foruse with the dual-independent powertrains disclosed herein. It will beunderstood that other types of vehicles may be used in combination withthe dual-independent powertrains disclosed herein.

Vehicle 30 includes a chassis 34 (also referred to as a vehicle frame)for support of powertrain 10 and the vehicle's occupants. Operator seat36 and passenger seat 37 are positioned such that the passenger seat isdirectly behind the operator seat. Alternatively the passenger seat 37may not be provided so as to add more storage capacity to the vehicle.The operator and passenger seats 36, 37 may be positioned closertogether than the front and rear seats of a conventional automobile inorder to provide a smaller vehicle footprint on the road. The operatorseat may be narrower in parts than a conventional automotive seat toallow the passenger's legs to comfortably straddle the operator seat. Afoot well 35 within the forward center area of the chassis 34 allows forcomfortable driver foot placement while lowering the driver seat. Thechassis may be formed of sheet material, tube steel, composites,corrugated plastics or other suitable material.

Two front wheels 39 positioned at or near the front of the vehicle areeach independently driven by one of the respective output shafts from adual-independent powertrain, such as powertrain 10, for example. In thisconfiguration, powertrain is powered by electric motors, which arepowered by one or more energy storage devices. An energy storage devicemay include a series or group of battery modules. Alternatively, othersuitable energy storage devices may be used within the context ofelectric motors, such as a fuel cell. An individual rear wheel 40 ispositioned along plane 17 at or near the rear of the vehicle. Plane 17is defined as a plane positioned at a centerline or middle of thechassis 34 along a long axis of the vehicle. Chassis 34 may besymmetrical about plane 17.

The components of the powertrain (including the drive sources of theoverall propulsion system of the vehicle) are arranged so as to provideballast for stability on the three-wheeled platform depicted in FIGS. 6and 7. Powertrain 10 has a center of mass that is positioned closer tothe front of the vehicle 30 than the axis defined by the first andsecond output shafts 18 a, 18 b and is lower to the ground than thecenter of mass of the chassis. In a preferred example at least 25% ofthe weight of the powertrain 10 may be positioned at a level below thecenter of gravity of the chassis 34.

The previously described powertrain 10 is a non-limiting example of adual-independent powertrain that may be incorporated into a vehicle.FIG. 8 depicts an internal view of another example dual-independentpowertrain 800 that may be incorporated into a vehicle. In contrast topowertrain 10, which included motor shafts or motor-interfacing shaftsthat were non-collinear, powertrain 800 is symmetric about a centralplane 802. Powertrain 800 similarly includes a dual-independenttransmission enclosure 810 that houses two transmissions that aremechanically decoupled from each other. It will be understood thataspects of previously described powertrain 10 may be used in combinationwith powertrain 800. For example, the various materials, assemblytechniques, and vehicle integration approaches described herein withrespect to powertrain 10 may be applied to powertrain 800.

Enclosure 810 includes a central frame 812, a first enclosure cover 814,and a second enclosure cover 816. First enclosure cover 814 interfaceswith central frame 812 to collectively define a first transmissionregion 820 of enclosure 810 on a first side of central frame 812. Secondenclosure cover 816 interfaces with central frame 812 to collectivelydefine a second transmission region 820 of enclosure 810 on a secondside of central frame 812, opposite the first transmission region 820.First and second transmission regions may form separate or combinedfluid-tight spaces in combination with central frame 812.

A first transmission 821 is housed within first transmission region 820of enclosure 810. First transmission 821 includes a firstmotor-interfacing shaft 822, a first drive-interfacing shaft 827, and afirst multi-stage gear train mechanically coupling the firstmotor-interfacing shaft 822 and the first drive-interfacing shaft 827.The first multi-stage gear train of first transmission 821 may includetwo or more speed reduction stages in an example configuration, such asdepicted in FIG. 8.

A second transmission 831 is housed within second transmission region830 of enclosure 810. Second transmission 831 includes a secondmotor-interfacing shaft 832, a second drive-interfacing shaft 837, and asecond multi-stage gear train mechanically coupling the secondmotor-interfacing shaft 832 and the second drive-interfacing shaft 837.The second multi-stage gear train of second transmission 831 may alsoinclude two or more speed reduction stages.

Central frame 812 is located along a central plane 802 of the enclosureand is disposed between first enclosure cover 814 and second enclosurecover 816. In this example, first transmission 821 and secondtransmission 831 are symmetric about the central plane, and each providethe same gear ratio and the same speed reduction. Second transmission831 is mechanically decoupled from first transmission 821 to providedual-independent powertrain components.

Powertrain 800 may further include or may interface with a firstelectric motor 880 including a first motor shaft 882 coupled to orintegrated with first motor-interfacing shaft 822, and a second electricmotor 884 including a second motor shaft 886 coupled to or integratedwith second motor-interfacing shaft 832. It will be understood thatpowertrain 800 may not include or may be provided without the two drivesources, such as electric motors 880 and 884. Furthermore, powertrain800 may include or may be combined with other suitable drive sources,including combustion engines.

A non-limiting advantage of using electric motors with thedual-independent powertrains disclosed herein is the ability for thefirst and second transmissions to have a single or fixed gear ratio, asfurther enabled by the more constant and broader speed vs. torquerelationship of electric motors as compared to combustion engines. Thissingle or fixed gear ratio may enable reduction in size, weight, cost,and complexity of each transmission individually as well as the overallsize, weight, cost, and complexity of the powertrain.

Powertrain 800 may further include or may interface with a first drivewheel that is coupled to or otherwise fixed to first drive-interfacingshaft 827, and a second drive wheel coupled to or otherwise fixed tosecond drive-interfacing shaft 837. In some examples, drive wheels maybe mechanically coupled with drive-interfacing shafts via an interveningdrive shaft and/or other intervening components. FIGS. 6 and 7 depictnon-limiting examples of drive wheels of a vehicle that may be coupledto first and second drive-interfacing shafts 827 and 837. It will beunderstood that powertrain 800 may be used in other types of vehicles,and that each of first and second drive-interfacing shafts 827 and 837may optionally be mechanically coupled with two or more drive wheels.

First motor-interfacing shaft 822 and first drive-interfacing shaft 827are located on an opposite side of central frame 812 from secondmotor-interfacing shaft 832 and second drive-interfacing shaft 837. Inthe example depicted in FIG. 8, each of first motor-interfacing shaft822, first drive-interfacing shaft 827, second motor-interfacing shaft832, and second drive-interfacing shaft 837 are parallel to each other.In symmetric configurations of powertrain 800, first drive-interfacingshaft 822 and second drive-interfacing shaft 832 are collinear, andfirst motor-interfacing shaft 827 and second motor-interfacing shaft 837are collinear. Also in symmetric configurations motor shafts 882 and 886are parallel to each other and collinear.

In at least some examples, first transmission 821 takes the form of afirst multi-stage gear train that includes a first larger intermediategear 825 and a first smaller intermediate gear 826 fixed to a firstintermediate shaft 824. In other examples, first transmission 821 maytake the form of a single stage gear train or a multi-stage gear trainhaving three or more stages.

The first multi-stage gear train of this example further includes afirst motor-side gear 823 fixed to first motor-interfacing shaft 822that meshes with first larger intermediate gear 825. In the exampledepicted in FIG. 8, first motor-side gear 823 is smaller than firstlarger intermediate gear 825, which provides a first stage of speedreduction from first motor-interfacing shaft 822 to first intermediateshaft 824. The first multi-stage gear train of this example furtherincludes a first drive-side gear 828 fixed to first drive-interfacingshaft 827 that meshes with first smaller intermediate gear 826. In theexample depicted in FIG. 8, first drive-side gear 828 is larger thanfirst smaller intermediate gear 826, which provides a second stage ofspeed reduction from first intermediate shaft 824 to firstdrive-interfacing shaft 827.

Second transmission 831 may also takes the form of a second multi-stagegear train that includes a second larger intermediate gear 835 and asecond smaller intermediate gear 836 fixed to a second intermediateshaft 834. In other examples, second transmission 831 may take the formof a single stage gear train or a multi-stage gear train having three ormore stages, and may be the same as the first transmission 821. In asymmetric configuration between first and second transmissions 821 and831, first larger intermediate gear 825 and second larger intermediategear 835 are the same size (and have the same quantity and configurationof teeth), and first smaller intermediate gear 826 and second smallerintermediate gear 836 are the same size (and have the same quantity andconfiguration of teeth).

The second multi-stage gear train of this example further includes asecond motor-side gear 833 fixed to second motor-interfacing shaft 832that meshes with second larger intermediate gear 835. In a symmetricconfiguration, first motor-side gear 823 and second motor-side gear 833are the same size (and have the same quantity and configuration ofteeth). In the example depicted in FIG. 8, second motor-side gear 833 issmaller than second larger intermediate gear 835, which provides a firststage of speed reduction from second motor-interfacing shaft 832 tosecond intermediate shaft 834. The second multi-stage gear train of thisexample further includes a second drive-side gear 838 fixed to seconddrive-interfacing shaft 837 that meshes with second smaller intermediategear 836. In a symmetric configuration between first and secondtransmissions 821 and 831, first drive-side gear 828 and seconddrive-side gear 838 are the same size (and have the same quantity andconfiguration of teeth). In the example depicted in FIG. 8, seconddrive-side gear 838 is larger than second smaller intermediate gear 836,which provides a second stage of speed reduction from secondintermediate shaft 834 to second drive-interfacing shaft 837.

In the example depicted in FIG. 8, each of the motor-side gears 823 and833 are helical gears and each of the larger intermediate gears 825 and835 are helical gears. Helical gears may be more suitable than spurgears at this first speed reduction stage to accommodate higher speeds.Also in the example depicted in FIG. 8, each of the drive-side gears 828and 838 are spur gears, and each of the smaller intermediate gears 826and 836 are spur gears. Spur gears may be suitable at this second speedreduction stage following speed reduction by the first speed reductionstage. It will be understood that the above examples are non-limiting,and any or all of the gears may be spur gears, helical gears, or othersuitable gear types in other implementations.

Each of the shafts or axles described herein may be supported by one ormore rotational bearings. Such bearings may take the form of thrustbearings in some examples. Bearings may include or may interface withone or more seals to provide a fluid-tight or fluid leak-resistiveboundary in combination with a shaft or axle.

Central frame 812 includes a first set of bearings 840 on the first sideof the central frame that respectively support and enable rotation offirst motor-interfacing shaft 822, first drive-interfacing shaft 827,and intermediate shaft(s) such as first intermediate shaft 824. Centralframe includes a second set of bearings 842 on the second side of thecentral frame that respectively support and enable rotation of secondmotor-interfacing shaft 832, second drive-interfacing shaft 837, andintermediate shaft(s) such as second intermediate shaft 834.

First enclosure cover 814 includes a set of bearings 844 thatrespectively support and enable rotation of first motor-interfacingshaft 822 (or a first motor shaft 880 coupled with shaft 822), firstdrive-interfacing shaft 827 (or a first drive shaft 890 coupled withshaft 927), and intermediate shaft(s) such as first intermediate shaft824. Second enclosure cover 834 includes a set of bearings 846 thatrespectively support and enable rotation of second motor-interfacingshaft 832 (or a second motor shaft 886 coupled with shaft 832), seconddrive-interfacing shaft 837 (or a second drive shaft 892 coupled withshaft 837), and intermediate shaft(s) such as second intermediate shaft834. Each of the bearings of the enclosure covers that supportmotor-interfacing shafts, motor shafts, drive-interfacing shafts, ordrive shafts that protrude from the internal transmission regions of theenclosure through the enclosure covers may be arranged within respectiveopenings formed in the enclosure covers to provide external access tothe shafts. Such bearings may include or interface with one or moreseals to retain transmission oil or fluid within the internaltransmission regions.

In the example depicted in FIG. 8, central frame 812 defines orotherwise includes one or more openings or pathways 874 that enablefluid communication between first transmission region 820 and secondtransmission region 830 to provide a shared fluid region. In thisexample, the shared fluid region may be accessed via an opening orpathway (e.g., a fill spout) that is defined or included on an exteriorwall of enclosure 810. As an example, a transmission fluid or oil may beadded via opening 870 formed in an enclosure cover, such as secondenclosure cover 816 (or alternatively enclosure 814 or central frame810), and a cap 872 may be used to seal opening 870. In examples where ashared fluid region is formed by first transmission region 820 andsecond transmission region 830 via an opening or pathway in centralframe 812, a single fill spout and a single fill operation may be usedto collectively supply transmission oil or fluid to both transmissionregions. The single fill spout or optionally a separate single drainspout may enable the oil or fluid to be collectively removed from thefirst and second transmission regions with a single drain operation.These features may be similarly incorporated into previously describedpowertrain 10 of FIGS. 1-7.

In at least some configurations, first enclosure cover 814 and secondenclosure cover 816 may be secured to opposite sides of central frame812 by way of one or more fasteners 860. FIG. 8 depicts an example inwhich bolts that are threaded into threaded holes in the central frameare used to secure the enclosure covers to the central frame. Thisfeature may be similarly incorporated into powertrain 10. FIGS. 9 and 10depicts another view of an example powertrain in which fasteners (e.g.,bolts) are used around a perimeter of an enclosure cover to secure theenclosure cover to a central frame.

FIG. 9 depicts a side view of an example dual-independent powertrain 900with an enclosure cover removed to reveal internal components.Powertrain 900 is a non-limiting example of previously describedpowertrain 800 of FIG. 8. Accordingly, powertrain 900 includes twoindependent transmissions. FIG. 10 depicts powertrain 900 with anenclosure cover 1010 installed.

A central frame 910 of powertrain 900 includes a central wall 912 and arim 914 that defines a portion of a transmission region 904 within whichtransmission 906 is housed. Central frame 910 is a non-limiting exampleof central frame 812 of FIG. 8. Rim 914 interfaces with a correspondingenclosure cover 1010 depicted in FIG. 10. Enclosure cover 1010 is anon-limiting example of enclosure covers 814 and 816 of FIG. 8. Rim 914includes openings 915 (e.g., threaded holes) formed therein to receivefasteners (e.g., threaded bolts) that secure enclosure cover 1010 tocentral frame 910. Central wall 912 may have one or more openings orchannels 917 formed therein that enable fluid to be exchanged withanother transmission region located on an opposite side of the centralwall. It will be understood that opening/channel 917 is a non-limitingexample, and that one, two or more openings or channels may be used thathave different locations from the location depicted in FIGS. 8 and 9.

Central wall 912 may include or otherwise accommodate a set of bearingsthat support and enable rotation of a motor-interfacing shaft 920, adrive-interfacing shaft 922, and optionally one or more intermediateshafts, such as intermediate shaft 924. Motor-interfacing shaft 920 is anon-limiting example of motor-interfacing shafts 822 and 832 of FIG. 8that interfaces with an electric motor or other suitable drive source.Drive-interfacing shaft 922 is a non-limiting example ofdrive-interfacing shafts 827 and 837 of FIG. 8 that interfaces with adrive wheel. Intermediate shaft 924 is a non-limiting example ofintermediate shafts 824 and 834.

Transmission 906 in FIG. 9 provides speed reduction from a drive sourceto a drive shaft by way of a fixed-ratio multi-stage gear train. In FIG.9, gears are depicted in simplified form, and may have any suitablequantity of teeth and relative sizing.

Motor-interfacing shaft 920 includes a motor-side gear 930 fixed thereonor integrated with the gear. Motor-side gear 930 is a non-limitingexample of motor-side gears 823 and 833 of FIG. 8. Drive-interfacingshaft 922 includes a drive-side gear 932 fixed thereon or integratedwith the gear. Drive-side gear 932 is a non-limiting example ofdrive-side gears 828 and 838 of FIG. 8. Intermediate shaft 924 includesa larger intermediate gear 934 and a smaller intermediate gear 936 fixedthereon or integrated with the gears.

Central frame 910 may include a variety of mounting elements (e.g., 940and 942) and/or mounting surfaces (e.g., 944) to mount the powertrain900 to a frame or chassis of a vehicle or other object.

Within FIG. 10, an example spatial relationship between the variousshafts or axles of the powertrain is depicted. An angle measurement 1024is depicted between a reference line 1020 formed betweendrive-interfacing shaft 922 and intermediate shaft 924, and a referenceline formed between intermediate shaft 924 and motor-interfacing shaft920. Angle measurement 1024 refers to the gear train angle, which is thesmallest angle measured between reference lines 1020 and 1022, with 180degrees being the maximum angle. Angle measurement 1024 may be less than90 degrees, 90 degrees, or greater than 90 degrees depending onimplementation. An angle of 180 degrees may be referred to as a flatconfiguration. An angle of less than 180 serves to reduce the overallsize of the powertrain in at least a first dimension, while potentiallyincreasing the size of the powertrain in a second dimension that isorthogonal to the first dimension. An angle of less than 90 degrees maybe referred to as a folded configuration that provides a compromisebetween a size of the powertrain in both orthogonal dimensions depictedin FIG. 10.

As previously described with reference to powertrain 10, adual-independent powertrain may be integrated into a vehicle, such as athree-wheeled vehicle. Within the context of an electric vehicle, suchas the three-wheeled vehicle 30 of FIGS. 6 and 7, each motor (e.g.,motors 16 a, b or 880, 884) and the motor-interfacing shafts thatinterface with those motors may be located at or closer to the front ofthe vehicle than the drive-interfacing shafts that interface with thedrive wheels. In this configuration, the center of mass of thepowertrain is in front of the front wheels. Additionally oralternatively, the center of mass of the powertrain may be located at orbelow the center of mass of the vehicle and/or at or below a height ofthe axles of the drive wheels relative to a ground surface.

The dual-independent powertrains disclosed herein may provide numerousbenefits that are not present in existing electric powertrains. Onebenefit is the shared similarity of the components of the dual drivesources, dual transmissions, and their respective gear trains. The useof the same components in each transmission reduces the cost of thepowertrain via a higher volume of parts manufactured and/or purchasedfor each powertrain. Additionally, using similar or identical componentsbetween transmissions reduces the complexity of the assembly process,thereby further reducing the cost of the powertrain.

The dual-independent powertrains disclosed herein provide a compact andefficient solution for parallel power delivery, particularly in foldedgear train configurations. Because each motor may be independentlycontrolled, the driving performance of the vehicle may be improved, forexample, by providing traction control to the vehicle. A wheel thatrequires more or less rotational force to stabilize the vehicle in roughterrain or during a turn, can make the necessary rotational speedadjustments without affecting the other wheel. The traction control maybe electronically controlled by a motor controller or vehicle controlsystem based on inputs from the vehicles steering angle and rotationalspeed of each wheel at any given moment in time.

Another advantage of disclosed dual-independent powertrains disclosedherein includes, without limitation, the incorporation of electronicallycontrolled anti-locking braking (ABS). The motor controller or vehiclecontrol system can switch the motors from acting as drive motors toacting as power generators. This power generation operations createresistive, counter rotational forces on the motor(s) through the geartrains, which serve to slow the vehicle. Because the wheels may beindependently controlled, if one wheel locks up, the control system canreduce the counter rotational force on that wheel without affecting thecounter rotational force on the other wheel This feature increases theperformance and safety of the vehicle, and gives the driver more controlof the vehicle without necessary requiring the addition of a separateanti-lock braking component. When the motors are acting as generatorsduring anti-locking braking operation or other forms of braking, theelectricity created can be stored in a battery pack or other suitableenergy storage device. This process of regenerative power brakingincreases the overall efficiency of the vehicle's power use, turning thevehicles momentum into usable electricity for later use.

It will be understood that the configurations and techniques describedherein are exemplary in nature. Specific examples are not to beconsidered in a limiting sense, because numerous variations arepossible. The subject matter of the present disclosure includes allnovel and nonobvious combinations and subcombinations of the variousconfigurations and techniques disclosed herein, as well as any and allequivalents thereof.

The invention claimed is:
 1. A powertrain for a vehicle, comprising: adual-independent transmission enclosure, including: a central frame, afirst enclosure cover interfacing with the central frame to collectivelydefine a first transmission region of the dual-independent transmissionenclosure on a first side of the central frame, and a second enclosurecover interfacing with the central frame to collectively define a secondtransmission region of the dual-independent transmission enclosure on asecond side of the central frame; a first transmission housed within thefirst transmission region of the dual-independent transmissionenclosure, and including a first motor-interfacing shaft, a firstdrive-interfacing shaft, and a first multi-stage gear train mechanicallycoupling the first motor-interfacing shaft and the firstdrive-interfacing shaft; a second transmission housed within the secondtransmission region of the dual-independent transmission enclosure thatis mechanically decoupled from the first transmission, and including asecond motor-interfacing shaft, a second drive-interfacing shaft, and asecond multi-stage gear train mechanically coupling the secondmotor-interfacing shaft and the second drive-interfacing shaft thecentral frame including a first set of bearings on the first side of thecentral frame that respectively support and enable rotation of the firstmotor-interfacing shaft and the first drive-interfacing shaft; and thecentral frame including a second set of bearings on the second side ofthe central frame that respectively support and enable rotation of thesecond motor-interfacing shaft and the second drive-interfacing shaft.2. The powertrain of claim 1, wherein the central frame is located alonga central plane of the dual-independent transmission enclosure and isdisposed between the first enclosure cover and the second enclosurecover.
 3. The powertrain of claim 2, wherein the first transmission andthe second transmission are symmetric about the central plane, and eachprovide the same gear ratio and the same speed reduction.
 4. Thepowertrain of claim 1, wherein the first enclosure cover includesbearings that respectively support and enable rotation of the firstmotor-interfacing shaft and the first drive-interfacing shaft, each ofthe bearings of the first enclosure cover arranged within respectiveopenings formed in the first enclosure cover to provide external accessto the first motor-interfacing shaft and the first drive-interfacingshaft; and wherein the second enclosure cover includes bearings thatrespectively support and enable rotation of the second motor-interfacingshaft and the drive-interfacing shaft, each of the bearings of thesecond enclosure cover arranged within respective openings formed in thesecond enclosure cover to provide external access to the secondmotor-interfacing shaft and the second drive-interfacing shaft.
 5. Thepowertrain of claim 1, wherein the first multi-stage gear trainincludes: a first larger intermediate gear and a first smallerintermediate gear fixed to a first intermediate shaft, the firstintermediate shaft supported by another bearing of the first set ofbearings of the central frame and another bearing of the first enclosurecover, a first motor-side gear fixed to the first motor-interfacingshaft that meshes with the first larger intermediate gear, wherein thefirst motor-side gear is smaller than the first larger intermediategear, and a first drive-side gear fixed to the first drive-interfacingshaft that meshes with the first smaller intermediate gear, wherein thefirst drive-side gear is larger than the first smaller intermediategear; and wherein the second multi-stage gear train includes: a secondlarger intermediate gear and a second smaller intermediate gear fixed toa second intermediate shaft, the second intermediate shaft supported byanother bearing of the second set of bearings of the central frame andanother bearing of the second enclosure cover, a second motor-side gearfixed to the second motor-interfacing shaft that meshes with the secondlarger intermediate gear, wherein the second motor-side gear is smallerthan the second larger intermediate gear, and a second drive-side gearfixed to the second drive-interfacing shaft that meshes with the secondsmaller intermediate gear, wherein the second drive-side gear is largerthan the second smaller intermediate gear.
 6. The powertrain of claim 5,wherein the first motor-side gear and second motor-side gear are thesame size; wherein the first larger intermediate gear and the secondlarger intermediate gear are the same size; wherein the first smallerintermediate gear and the second smaller intermediate gear are the samesize; and wherein the first drive-side gear and second drive-side gearare the same size.
 7. The powertrain of claim 5, wherein each of themotor-side gears and each of the larger intermediate gears are helicalgears; and wherein each of the drive-side gears and each of the smallerintermediate gears are spur gears.
 8. The powertrain of claim 1, whereinthe central frame defines one or more openings or pathways that enablefluid communication between the first transmission region and the secondtransmission region to provide a shared fluid region.
 9. The powertrainof claim 1, further comprising: a first electric motor including a firstmotor shaft coupled to the first motor-interfacing shaft; and a secondelectric motor including a second motor shaft coupled to the secondmotor-interfacing shaft.
 10. The powertrain of claim 1, wherein thefirst drive-interfacing shaft and the second drive-interfacing shaft arecollinear.
 11. The powertrain of claim 10, wherein the firstmotor-interfacing shaft and the second motor-interfacing shaft arecollinear.
 12. The powertrain of claim 11, wherein the firstmotor-interfacing shaft and the first drive-interfacing shaft arelocated on an opposite side of the central frame from the secondmotor-interfacing shaft and the second drive-interfacing shaft.
 13. Thepowertrain of claim 1, wherein the first motor-interfacing shaft, thefirst drive-interfacing shaft, the second motor-interfacing shaft, andthe second drive-interfacing shaft are parallel to each other.
 14. Thepowertrain of claim 1, wherein the first multi-stage gear train and thesecond multi-stage gear train each includes two or more speed reductionstages.
 15. The powertrain of claim 1, further comprising: a first drivewheel coupled to the first drive-interfacing shaft; and a second drivewheel coupled to the second drive-interfacing shaft.
 16. A three-wheeledelectric vehicle, comprising: a vehicle frame; a front pair of drivewheels located at or near a front end of the vehicle frame on oppositesides of a central plane of the three-wheeled electric vehicle; a singlerear wheel located at or near a rear end of the vehicle frame; and adual-independent powertrain located at the front end of the vehicleframe, the dual-independent powertrain comprising: a central framelocated along the central plane of the three-wheeled electric vehicle, afirst enclosure cover interfacing with the central frame to collectivelydefine a first transmission region on a first side of the central frame,a first transmission housed within the first transmission region, andincluding a first motor-interfacing shaft, a first drive-interfacingshaft coupled to or interfacing with a first drive wheel of the frontpair of drive wheels, and a first multi-stage fixed-ratio gear trainmechanically coupling the first motor-interfacing shaft and the firstdrive-interfacing shaft, a first electric motor coupled to orinterfacing with the first motor-interfacing shaft on a first side ofthe central plane, the first motor and the first motor-interfacing shaftlocated at or closer to the front of the vehicle than the firstdrive-interfacing shaft, a second enclosure cover interfacing with thecentral frame to collectively define a second transmission region on asecond side of the central frame, a second transmission housed withinthe second transmission region that is mechanically decoupled from thefirst transmission, and including a second motor-interfacing shaft, asecond drive-interfacing shaft coupled to or interfacing with a seconddrive wheel of the front pair of drive wheels, and a second multi-stagefixed-ration gear train mechanically coupling the secondmotor-interfacing shaft and the second drive-interfacing shaft, and asecond electric motor coupled to or interfacing with the secondmotor-interfacing shaft on a second side of the central plane, thesecond motor and the second motor-interfacing shaft located at or closerto the front end of the vehicle than the second drive-interfacing shaft.17. The three-wheeled electric vehicle of claim 16, wherein the firstdrive-interfacing shaft is located on the first side of the centralplane and the second drive-interfacing shaft is located on the secondside of the central plane.
 18. The three-wheeled electric vehicle ofclaim 16, wherein the central frame defines one or more openings orpathways that enable fluid communication between the first transmissionregion and the second transmission region to provide a shared fluidregion.
 19. A powertrain for a vehicle, comprising: a dual-independenttransmission enclosure, including: a central frame, a first enclosurecover interfacing with the central frame to collectively define a firstfluid-tight region on a first side of the central frame, and a secondenclosure cover interfacing with the central frame to collectivelydefine a second fluid-tight region on a second side of the centralframe; a first transmission housed within the dual-independenttransmission enclosure, and including a first motor-interfacing shaft, afirst drive-interfacing shaft, and a first multi-stage gear trainmechanically coupling the first motor-interfacing shaft and the firstdrive-interfacing shaft; and a second transmission housed within thedual-independent transmission enclosure that is mechanically decoupledfrom the first transmission, and including a second motor-interfacingshaft, a second drive-interfacing shaft, and a second multi-stage geartrain mechanically coupling the second motor-interfacing shaft and thesecond drive-interfacing shaft; wherein the first motor-interfacingshaft and the second drive-interfacing shaft are located on the firstside of the central frame; wherein the second motor-interfacing shaftand the first drive-interfacing shaft are located on a second side ofthe central frame; wherein the first motor-interfacing shaft and thesecond motor-interfacing shaft are not collinear with each other; andwherein the first drive-interfacing shaft and the seconddrive-interfacing shaft are collinear with each other.